3Y-TZP specimens were pulled at temperatures ranging from 1623 to 1723 K with strain rates ranging from 3.3x10(-5) to 6.7x10(-3) s(-1) to Various nominal strains. Characterization of cavities was conducted for gauge section of deformed specimens by SANS method and conventional ones including density measurement method and scanning electron microscopy analysis. The volume fraction of cavities and the evolution of cavity shapes were evaluated from the SANS results as a function of nominal strain for deformations carried out under the same superplastic condition. These behaviors were also discussed with the change in deformation condition. It is found that the SANS method is the most excellent technique for cavity characterization: the SANS method can measure the characteristics of cavities with better statistics and can measure flat cavities or fine defects which are quite difficult to identify by the conventional methods.